The constituents of senna leaves / by Frank Tutin.

  • Tutin, Frank.
Date:
[1913?]
Catalogue details

Licence: Public Domain Mark

Credit: The constituents of senna leaves / by Frank Tutin. Source: Wellcome Collection.

    5/22 page 2008
    water and distilled in a current of steam, when a quantity (1*5 grams) of a dark-coloured essential oil was obtained, which possessed a strong aromatic odour. There then remained in the distillation flask a dark-coloured aqueous liquid (A) and a quantity of a soft, dark green resin (Z?). These products were separated when cold, and the resin washed several times with aqueous ammonium sulphate, the washings being kept separate from the main bulk of the aqueous liquid. This procedure was necessitated by the fact that the resin formed an inseparable emulsion on attempting to wash it with water. Examination of the Aqueous Liquid (A). The aqueous liquid, after concentration under diminished pres¬ sure, was extracted many times with ether. These ethereal liquids were united, the greater part of the solvent removed, and the residue largely diluted with light petroleum (b. p. 35—50°), when the greater part of the dissolved material was precipitated as a brown solid. On decanting and concentrating the supernatant liquid, and again treating it with light petroleum, further small quantities of a similar solid were obtained, which were added to the first portion. The petroleum liquid was finally evaporated, the residue dissolved in ether, and the ethereal solution shaken succes¬ sively with aqueous ammonium carbonate, sodium carbonate, and potassium hydroxide. The ammonium carbonate extract was acidified, and extracted with ether, when a yellow, viscid product was obtained. The latter was digested with warm water and treated with animal charcoal, when the filtrate yielded a small amount of an acid, which separated in colourless needles, melting at 155°, and was identified as salicylic acid. The sodium carbonate extract yielded only an amorphous, brown powder, but on acidifying the liquid obtained by means of aqueous potassium hydroxide a product was obtained, which was found to consist largely of aloe-emodin. This substance was subsequently obtained in larger amount, and its isolation will be described later. Isolation of Rhein, C14H502(0H)2-C02H. The above-mentioned brown solid which had been precipitated by means of light petroleum was digested with a considerable volume of ether, when a quantity (about 0’5 gram) of a yellowish- brown powder remained undissolved. The latter was collected, and dissolved in pyridine, from which it separated in orange- coloured needles, melting at about 318°. (Found, C=63-2; H = 29. Ci5H806 requires C = 63 4; H = 2‘8 per cent.)
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